Process for hydrocarbon conversion



mine and bromine compounds.

Patented Feb. 28, 1950 PROCESS FOR HYDROCARBON I CONVERSION Hillis 0. Folkins, Skokie, Ill., assignor to' The Pure Oil Company, Chicago, 111., a corporation of Ohio N Drawing. Application? June 20, 1945, Serial No. 600,639

3 Claims. (01. 196-52) This invention relates to cracking of liquid hydrocarbons and more particularly to the cracking of hydrocarbon oils to gasoline boiling hydro carbons in the presence of small amounts of bro- It is known to use bromine and bromine compounds as promoters or catalysts in the cracking of hydrocarbons in order to convert the hydrocarbons into more unsaturated hydrocarbons or into hydrocarbons of lower boiling point. Although bromine and bromine compounds are in general good cracking promoters, many of these substances have the disadvantage of deleteriously affectin the lead susceptibility of the gasoline produced if used as cracking sensitizers in too large amounts.

I have discovered that if the bromine or bromine compound used as promoter is kept below 7 an amount equivalent to 0.1% by weight of bros Although bromine and bromine compounds of the class before mentioned are in general useful, I prefer to use bromine compounds containing only carbon, hydrogen and bromine in the molecule and more particularly the alkyl bromides, since these" compounds are almost as active in accelerating cracking whenfused in very small amounts as whenused in amounts considerably in excess of 0.1 %'by weight.

In accordance with my invention, bromine and bromine compounds of the class described are used in amounts equivalent to not more than 0.1% by weight of bromine, based on the liquid or' oil to be cracked. Amounts equivalent to as low as .001% by weight of bromine are effective in sensitizing the cracking reaction.

sensitizers may be mixed with the hydrocarbon oil either in the liquid or vapor state prior to charging the oil to the cracking zone, or the sensitizer may be separately injected directly into the reaction zone. Although we prefer to use sensitizers which are in the same physical state as the hydrocarbons undergoing cracking at rethe rate of cracking of hydrocarbons in thermal cracking operations.

A further object of the invention is to provide a simple method for increasing the yield of motor fuel in thermal'cracking operations without'deleteriously affecting the octane number or lead susceptibility of the motor fuel produced.

Other objects 'of the invention will become manifest from the following description.

In accordance with my invention, liquid hydrocarbons such as gas oil, heavy naphtha or crude residuum are subjected to cracking conditions of time, temperature and pressure in the presence of a substance selected from the group consisting of bromine, halogen bromides, such as iodinev monobrom'ide, hydrogen bromide and organic bromine compounds containing only carbon, hydrogen and halogen in the molecule. As examples of bromine compounds which are suitable are mentioned: ethylene chlorobromide, trimethylene ylene bromide and tribromomethylene.

action temperature, sensitizers may be used which exist in a different physical state from that of the hydrocarbons undergoing reaction. The sensitizers, if soluble. in the hydrocarbons undergoing cracking, may be dissolved therein prior to passage through the reaction zone, or may be dissolved in a small portion of the oil and the solution fed into the main stream. If the sensitizer is a solid which is insoluble in the hydrocarbon oil undergoing cracking, a slurry of finely comminuted sensitizer in a portion of the oil may be fed in desired proportions into the main stream or injected directly into the cracking zone. Where vapor phase cracking is carried out, sensitizers which readily vaporize are preferably used. The sensitizer is preferably introduced into the oil or vapor at such places and in such manner that decomposition of the sensitizer does not occur until it is in contact with the oil at cracking temperature. One method of accomplishing this is to flash-inject the sensitizer at a temperature below its decomposition temperature into the cracking zone.

Cracking with sensitizers in accordance with my invention may be carried out under superatmospheric, atmospheric or sub-atmospheric pressure and at temperatures ranging from the lowest temperature at which cracking will occur, namely, approximately 650 F., to temperatures of approximately 1200" F. I prefer to crack at gasoline are higher at high pressures than at low pressure. Pressures up to 2000 pounds per square inch or higher may be used.

In order to demonstrate the effect of sensitizers falling within the scope of the invention in the cracking of oil when used in amounts within and above the limits of the invention, a number of runs were made in a continuous laboratory cracking apparatus using Pennsylvania gas oil as charging stock. The runs were made at a temperature of 475 C., at a pressure of 500 pounds per square inch gauge, in the cracking zone. The cracking zone was a piece of three inch stainless steel pipe having a length of approximately 9.25 inches. The apparatus contained a preheating coil in which the oil and promoter were heated to reaction temperature before entering the reactor.

In one series of runs, ethylene chlorobromide was used as a sensitizer in different amounts and compared with a blank run in which no sensitizer was used. This series of runs is designated in the following table as Series No. 1.

Another series of runs was made, designated as Series No. 2, using br-omocyclohexane as sensitizer. This series also included a blank run containing no sensitizer.

A third series of runs was made, designated as Series No. 3, in which propylene bromide was used. This series also included a blank run containing no sensitizer.

In the table the sum of the first four columns under Products recovered wt. percent of charge" in some cases is slightly less than the Total under 400 F. because of a small loss incurred during fractionation which is attributed to fractions boiling under 400 F.

30 tively, of bromocyclohexane, is very poor.

making a total of 19.6% as against 23.1% for the run in which 0.05% by weight of ethylene chlorobromide was used.

Examination of the octane numbers of the gasoline with and without tetraethyl lead shows that in all cases in which a sensitizer was used,

the clear octane number was higher than that of the motor fuel fraction boiling between 100 and 400 F. produced without sensitizer. It is significant, however, that the lead susceptibility of the motor fuel produced with amounts of sensitizers equivalent to more than 0.1% by weight of bromine was very poor; whereas, the leaded octane numbers of the fuel produced with 0.05 weight percent of sensitizer are superior to those of the fuel produced without sensitizers.

Considering now the second series in which bromocyclohexane was used as sensitizer, it will be seen that the lead susceptibility of the fuel produced with 0.7 and 0.5% by weight, respec- The octane number of the leaded fuel produced with 0.2% by weight of bromocyclohexane is poorer than that produced without bromocyclohexane for all amounts of tetraethyl lead except 3 cc.

Since 0.2% by weight of bromocyclohexane is equivalent to 098% by weight of bromine, it is on the border line of the upper limit of appli- Table Products Recovered Wt. Percent of Charge Run 'Percent by Charge Serles Sensitizer Wt. of Sensi- Rate in T t 1 No. tizer Lbs/Hr. o. and 0 Liquid to 100-409 F. 4oo=-eso F. Resi- Lighter 4 100 E. P. Fractlon Fraction due 63,

1 Ethylene chlorobromide..- l. 0 .883 2. 3 0. 7 3. 7 20. 6 63.8 7. 9 28.3 1 do 0. 5 6. 889 2.1 0. 6 3. 5 19.1 65.3 9. 4 25. 3 1 0.2 6. 876 2. 4 0. 7 1. 4 22.8 64.9 7. 5 27. 6 1 0. 05 6. 878 2. 4 0. 7 3.1 20. 0 66. 2 7. 6 26. 2 1 6.883 2. 5 0.8 3.1 16.5 69.3 7. 5 23. 2 2 0. 7 6. 894 2.1 0. 6 2. 9 21.6 67. 5 5.1 27. 4 2 0. 5 6.887 2.1 0.6 3.1 21. 2 65. 2 7. 5 27. 3 2 0.2 6. 872 2. 4 0. 7 1. 8 22. 9 64. 8 7. 4 27.8 2 0.1 6. 854 2. 6 0. 8' 3. 4 20. 5 61.7 10. 8 27.5 2 0. 05 6. 860 2. 5 0. 7 3. 2 19. 9 64.1 9. 4 26. 5 None 6.801 2. 5 0. 7 1. 5 17. 6 66. 4 11.2 22. 4 Propylene bromide. 1. 0 6. 894 2. 1 0. 6 1. 4 23. 5 68. 2 4. 2 27 6 do 0. 5 6. 894 2. 3 0. 7 3. 3 20. 9 57. 4 14.8 27.8 do 0.3 6.872 '2. 4 0. 7 3. 7 22.1 60. 1 10.9 29.0 0. 2 6.832 2. 4 0. 7 3. 4 20.3 63. 1 10.0 26. 9 do 0.1 6. 859 2. 4 0. 7 3. 2 20.3 63.3 9.8 26. 9 None 6.887 2. 6 0.7 3.3 16. 2 66. 8 10.1 23.1

A. S. T. M. Octane Nos. pf 400 F. Fractions Containing P girilfii Percent Un- %%eractive om saturates in n ex 100 Run Series No. Sens1t1zer E Frac 100 400D 0 R No. 0.5 cc 1.0 cc. 2.0 cc. 3.0 00. tion Fraction tion T. E. L '1. E L T. E. L. T. E. L. E.

1 Ethylene chlorobromide-.- 62.2 62.8 64.3 112 37.4 1. 4243 1 2o 63. 3 63. 5 64. 3 113 36. 9 1. 4209 n 1 r1n 58. 4. 62. 6 65. 4 69. 4 72. 0 114 31. 7 1. 4217 1 None 55. 4 59.6 63.7 67.2 70.8 113 33. 5 1. 4232 2 Bromocyclohexane 62. 6 62.9 63. 2 64. 3 67. 2 113 33.0 1. 4220 2 (1n 58. 7 58.5 58.3 59.6 60.1 116 30.3 1.4271 2 do 69. 4 60.4 63. 2 68.0 72. 9 114 32. 5 1. 4202 2 do 58. 4 62. 2 65. 2 70. 4 72. 9 115 32. 2 1. 4210 2 rln 59. 6 63. 2 66. 9 70.3 73. 6 114 36.1 1. 4169 2 None 57. 6 62.4 66. 3 70.0 71.9 112 31.9 1. 4181 3 Propylene bromide 60.0 60.0 60.0 59.8 59. 5 113 28. 9 1. 4200 '4 rin 60.3 60.4 113 30. 6 1. 4203 3 (in 61.6 62.6 113 31. 4 1. 4207 3 rin 61. 8 61. 9 62. 0 64. 8 69. 2 114 32. 4 1. 4189 '4 do 61. 5 62. 7 64.0 70. 7 74.0 115 32. 3 1. 4200 3 None 58. 0 62.4 66. 4 71.2 73. 2 113 31.1 1. 4172 cants critical range. The improvement in the octane number of leaded fuels is noticeable in the .case of the motor fuels produced with 0.1% and .05% by weight of bromocyclohexane.

In the series of runs in which propylene bromide was used as sensitizer, it is again apparent that with amounts of propylene bromide equivalent to more than 0.1% by weight of bromine, the lead susceptibilities of the motor fuel are poor and the octane ratings of the motor fuel containing lead are poorer than those of the motor fuel made without propylene bromide. On the other hand, the octane number of the motor fuel made using 0.1% by weight of propylene bromide is of the same magnitude as that of the motor fuel made without propylene bromide.

The difference in lead susceptibility between gasoline made with the larger and smaller amounts of promoters is all the more remarkable in view of the similarity in the aniline points and refractive indexes of the various gasoline fractions. It is known in general that unsaturates have poorer lead susceptibility than saturated hydrocarbons, but from analyses, as shown in the table, it does not appear that the unsaturated content is the eifective cause of the difference in lead susceptibility of the gasoline fractions.

It will be seen, therefore, that I have discovered that the yield of motor fuel in thermal cracking of hydrocarbons can be readily improved without deleteriously affecting the motor fuel by cracking oil in conventional type thermal cracking operations in the presence of very small amounts of bromine and certain type bromine compounds as the sole cracking catalyst or promoter.

It is claimed 1. The method .of cracking hydrocarbon liquid to hydrocarbons within the gasoline boiling range comprising, subjecting said liquid to cracking conditions of time, temperature and pressure in the presence of bromocyclohexane in amount based on the liquid undergoing cracking equiva- 6 lent to not more than 0.1 per cent by weight of bromine, as the sole catalyst present during the reaction.

2. The method of cracking petroleum oil boiling above the gasoline boiling range to gasoline boiling hydrocarbons comprising, subjecting said oil to temperatures of the order of 650 to 1200 F. for a period of time sufficient to obtain a substantial yield of gasoline boiling hydrocarbons in the presence of brominated cyclohexane in an amount equivalent to 0.001 to 0.1 per cent by Weight of bromine based on the oil, said promoter being the sole catalyst present during the reaction.

3. The method of cracking petroleum oil boiling above the gasoline boiling range to gasoline boiling hydrocarbons comprising, subjecting said oil to temperatures of the order of 650 to 1200 F. for a period of time sumcient to obtain a substantial yield of gasoline boiling hydrocarbons in the presence of bromocyclohexane in an amount equivalent to 0.001 to 0.1 per cent by weight of bromine based on the oil, said promoter being the sole catalyst present during the reaction.

HILLIS O. FOLKINS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,925,421 Peski Sept. 5, 1933 2,213,345 Marschner Sept. 3, 1940 2,295,752 Parkhurst Sept. 15, 1942 2,313,092 Rice Mar. 9, 1943 2,402,034 Folkins et al. June 11, 1946 FOREIGN PATENTS Number Country Date 406,006 Great Britain Feb. 7, 1934 

1. THE METHOD OF CRACKING HYDROCARBON LIQUID TO HYDROCARBONS WITHIN THE GASOLINE BOILING RANGE COMPRISING, SUBJECTING SAID LIQUID TO CRACKING CONDITIONS OF TIME, TEMPERATURE AND PRESSURE IN THE PRESENCE OF BROMOCYCLOHEXANE IN AMOUNT BASED ON THE LIQUID UNDERGOING CRACKING EQUIVALENT TO NOT MORE THAN 0.1 PER CENT BY WEIGHT OF BROMINE, AS THE SOLE CATALYST PRESENT DURING THE REACTION. 